Zhang Yuxi, Qi Kezong, Jing Yawei, Zuo Jiakun, Hu Jiangang, Lv Xiaolong, Chen Zhaoguo, Mi Rongsheng, Huang Yan, Yu Shengqing, Han Xiangan
Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai, 200241, People's Republic of China.
College of Animal Science and Technology, Anhui Agricultural University, Hefei, 230036, People's Republic of China.
AMB Express. 2017 Oct 10;7(1):188. doi: 10.1186/s13568-017-0486-y.
The luxS gene is required for autoinducer-2 (AI-2) synthesis in many bacterial species. AI-2 is taken up by a specific receptor to regulate multiple bacterial activities. However, the lack of methods to identify AI-2 receptors has impeded investigations into the roles of AI-2. Here, a luxS mutant of Escherichia coli strain BL21 (DE3) was constructed (named BL21∆luxS), and the recombinant LsrB protein of Salmonella enterica was expressed in BL21∆luxS and BL21 cells, which were named LsrB (BL21∆luxS) and LsrB (BL21), respectively. The results of the activity of recombinant LsrB binding showed that LsrB (BL21) bound to endogenous AI-2 (produced from BL21 strain), while LsrB (BL21∆luxS) did not (as BL21∆luxS cannot produce AI-2). However, the results of recombinant LsrB binding showed that LsrB (BL21∆luxS) can bind exogenous AI-2, which was released from LsrB (BL21∆luxS) at 55 °C for 10 min, while LsrB (BL21) could not bind exogenous AI-2 (due to binding of endogenous AI-2 before). Furthermore, analysis of the thermal stability of AI-2 showed that that AI-2 activity was relatively high at incubation temperatures below 65 °C. These findings will be beneficial for screening of new AI-2 receptors in different bacterial species.
在许多细菌物种中，自诱导物-2（AI-2）的合成需要luxS基因。AI-2通过特定受体被摄取以调节多种细菌活动。然而，缺乏鉴定AI-2受体的方法阻碍了对AI-2作用的研究。在此，构建了大肠杆菌BL21（DE3）菌株的luxS突变体（命名为BL21∆luxS），并在BL21∆luxS和BL21细胞中表达肠炎沙门氏菌的重组LsrB蛋白，分别命名为LsrB（BL21∆luxS）和LsrB（BL21）。重组LsrB结合活性的结果表明，LsrB（BL21）与内源性AI-2（由BL21菌株产生）结合，而LsrB（BL21∆luxS）不结合（因为BL21∆luxS不能产生AI-2）。然而，重组LsrB结合的结果表明，LsrB（BL21∆luxS）可以结合外源性AI-2，其在55℃下从LsrB（BL21∆luxS）释放10分钟，而LsrB（BL21）不能结合外源性AI-2（由于之前内源性AI-2的结合）。此外，对AI-2热稳定性的分析表明，在低于65℃的孵育温度下AI-2活性相对较高。这些发现将有助于在不同细菌物种中筛选新的AI-2受体。
